Method and apparatus for increasing the strength of phase-based watermarking of an audio signal

Abstract

A challenge of audio watermarking systems in which an acoustic path is involved is the robustness against microphone pickup in case of surrounding noise. The strength of phase-based watermarking is increased by determining a masking threshold for a current frequency bin in a frequency / phase representation changing the phase based on that masking threshold and an allowed phase change value, calculating an allowed magnitude change value for the current frequency bin and calculating from an audio quality level value a magnitude change scaling factor for the magnitude change value, and increasing its magnitude accordingly.

Description

TECHNICAL FIELD[0001]The invention relates to a method and to an apparatus for increasing the strength of phase-based watermarking of an audio signal.BACKGROUND[0002]A challenge of audio watermarking systems in which an acoustic path is involved is the robustness against microphone pickup. Especially in case of surrounding noise, it is very difficult to detect a watermark embedded in a watermarked signal that is played back via loudspeaker, cf. [1].SUMMARY OF INVENTION[0003]A problem to be solved by the invention is to improve the detection of watermark data that is embedded in a watermarked audio signal. This problem is solved by the method disclosed in claim 1. An apparatus that utilises this method is disclosed in claim 2.[0004]Advantageous additional embodiments of the invention are disclosed in the respective dependent claims.[0005]The invention is related to watermark detector compatible robustness increase of phase based watermarking systems. For increasing the robustness of ...

AI Technical Summary

Benefits of technology

The invention is about improving the accuracy and reliability of watermark detection in noisy environments. It uses both the phase and magnitude of the original audio signal to create a more robust watermark. This is done by increasing the masking threshold, which determines which parts of the audio signal can survive the acoustic path transmission. By increasing the masking threshold and reducing the desired audio quality, the system becomes more robust against environmental noise. This also makes it easier to embed the watermark in already existing detection systems. Overall, the invention ensures better accuracy and reliability of watermark detection in various signal processing operations like lossy compression and filtering.

Problems solved by technology

A challenge of audio watermarking systems in which an acoustic path is involved is the robustness against microphone pickup.

Especially in case of surrounding noise, it is very difficult to detect a watermark embedded in a watermarked signal that is played back via loudspeaker, cf.

Images